1. Field of the Invention
The present invention relates to the assembly and installation of precast concrete segments used in construction activities, such as bridge and highway construction. More particularly, the present invention relates to couplers for use in joining the end of a duct of such precast concrete segments to a steel plate, to a bar or to an anchor casting.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98.
Precast segmental bridges are known and commonly used throughout the world as a means to forge roadways through mountainous terrain or cross rivers or other barriers. Such bridges are typically constructed in accordance with the following sequence. First, series of upright piers are formed along the bridge span. Thereafter, cantilevered bridge sections are built out of each pier by successively mounting the precast segments to previously completed bridge components and post-tensioning the segments together. The cantilevered bridge segments are build out from each pier in a symmetrical fashion so that the piers are not subjected to undue bending loads. When the cantilevered sections are complete, the ends thereof are post-tensioned together to form a continuous bridge deck. Typically, two such bridge spans are constructed to accommodate the two directions of travel.
During the formation of the concrete segments, it is often necessary to apply steel bars, anchors, bulkheads, or plates thereto. As such, such steel structures are embedded in the concrete during the formation of the particular concrete segment. As such, a need has developed whereby a duct system (including the duct coupler) is joined to the steel structure prior to the pouring of the concrete for the particular concrete segment. It is important, under such circumstances, that the coupler be formed at the side surface of the concrete segment. In this manner, it is important to be able to releasably retain the coupler of the particular duct against the steel structure during the formation of the concrete segment.
During the formation of such concrete segments, it is important to be able to establish proper seals such that water, or other liquid, associated with the pouring of the concrete does not infiltrate the duct or into the interior bore of the steel structure. If any such leakage should occur, then such leakage could corrode the surfaces of the steel structure or could interfere with the ability to properly post-tension the cables extending through the ducts thereof. It is also it is also important to maintain the duct, along with the duct coupler in a proper position during the pouring of the concrete for the concrete segment.
The ability to avoid air and liquid intrusion into the interior of the duct it is very important in such multi-strand, precast concrete segmental structures. Since the structure is often used on bridges or elevated structures, the post-tensioning cables can be subject to a great deal of exposure from the elements. For example, if the bridge structures are associated with roads traveled by motor vehicles, then there is often the application of salt onto the highway. The salt, when dissolved in water, can leach through the area between this structure segments and into the duct so as to deteriorate the post-tensioning cables over time. As the post-tensioning cables become corroded, they can weaken so as to potentially cause the failure of the segmental structure. Past experience with such structures has shown that the primary area of leakage would be in those cracks formed between those matched concrete segments. As such, it is particularly important to provide a coupler for use in association with the polymeric ducts which will effectively prevent any liquid intrusion from entering the interior of the ducts and adjacent to the post-tensioning cables.
In the past, various patents have issued to the present inventor relating to such duct couplers and segmental construction systems. For example, U.S. Pat. No. 5,474,335, issued on Dec. 12, 1995 to the present inventor, describes a duct coupler with hinged interconnected locking rings. The coupler includes a body, flexible cantilevered sections on the end of the body adapted to pass over annular protrusions on the duct, and locking rings for locking the cantilevered flexible sections into position. As such, the coupler can be locked onto the duct.
U.S. Pat. No. 5,775,849, issued on Jul. 7, 1998 to the present inventor, teaches a duct system for post-tension rock anchorage systems that includes a first duct having a plurality of corrugations extending radially outwardly therefrom, a second duct having a plurality of corrugations extending radially outwardly therefrom, and a tubular body threadedly receiving the first duct at one end and threadedly receiving the second duct at the opposite end. The tubular body has a first threaded section formed on an inner wall of the tubular body adjacent one end of the tubular body and a second threaded section formed on the inner wall of the tubular body adjacent an opposite end of the tubular body. The threaded sections are formed of a harder polymeric material than the polymeric material of the first and second ducts.
U.S. Pat. No. 5,954,373, issued on Sep. 21, 1999 to the present inventor, describes a duct coupler apparatus for use on multi-strand post-tensioning systems. The coupler includes a tubular body with an interior passageway between a first open end and a second open end. A shoulder is formed within the tubular body between the open ends. A seal is connected to the shoulder so as to form a liquid-tight seal with a duct received within one of the open ends. A compression device is hingedly connected to the tubular body for urging the duct into compressive contact with the seal. The compression device has a portion extending around an exterior of the tubular body. The compression device includes an arm with an end hingedly connected to the tubular body and having an abutment surface adjacent the end. The arm is movable between a first position extending outwardly of an exterior of the tubular body and a second position aligned with an exterior of the tubular body.
U.S. Pat. No. 6,752,435, issued on Jun. 22, 2004 to the present inventor, describes an asymmetrical coupler apparatus for use with precast concrete segmental construction. This coupler system includes a first duct, a first coupler member extending over and around an exterior surface of the first duct and having an end opening adjacent an end of the first duct, a second duct, a second coupler member extending over and around in exterior surface of the second duct and an end opening adjacent to an end of the second duct, and a gasket received in the ends of the first and second coupler members. The gasket serves to prevent liquid from passing between the ends of the coupler members into an interior of either of the first and second ducts. An external seal is affixed to an opposite end of the first coupler member and affixed to an exterior surface of the first duct. An internal seal is interposed in generally liquid-tight relationship between an interior surface of the second coupler member and an exterior surface of the second duct.
U.S. Pat. No. 6,764,105, issued on Jul. 20, 2004 to the present inventor, describes a duct coupler apparatus for use with precast segmental concrete construction. This coupler member includes a first duct, a first coupler member extending over and around an exterior surface of the first duct and having a seat opening adjacent an end of the first duct, a second duct, a second coupler member extending over and around an exterior surface of the second duct and a seat opening adjacent an end of the second duct, and a gasket received in the seats of the first and second coupler members. An external seal is affixed to an opposite end of the first coupler member and affixed to an exterior surface of the first duct. The seats of the first and second coupler members have slot facing one another. The gasket is received within the slots.
U.S. Pat. No. 6,834,890, issued on Dec. 28, 2004 to the present inventor, shows a coupler apparatus for use with a tendon-receiving duct in a segmental precast concrete structure. This coupler apparatus includes a coupler body having an interior passageway for receiving the duct therein. The coupler body has a generally U-shaped channel formed at one end thereof. The coupler element has a connector element formed on an interior thereof adjacent one end the coupler body so as to allow the coupler element to receive a variety of implements for the formation of the precast concrete segment.
U.S. Pat. No. 6,874,821, issued on Apr. 5, 2005 to the present inventor, shows a coupler apparatus for use with precast concrete segmental construction. This coupler apparatus has a first duct, a first coupler member extending over and around the first duct, a second duct, a second coupler member extending over and around the second duct, and a gasket received at the ends of the first and second coupler members so as to prevent liquid from passing between the coupler members into an interior of either of the ducts. The ducts extend at a non-transverse acute angle with respect to the ends of the coupler members. Heat shrink seals are affixed to the opposite ends of the coupler member so as to secure the coupler members to the ducts in liquid-tight relationship. The ends of the coupler members have generally V-shaped grooves facing each other.
U.S. Pat. No. 7,267,375, issued on Sep. 11, 2007 to the present inventor, provides a duct coupler apparatus for joining the ends of a pair of ducts together in end-to-end relationship. This apparatus has a collar with a first end portion and a second end portion. A first coupler element is translatably secured to an exterior of the collar for moving the first end portion between the first and second positions. A second coupler element is translatably secured to the exterior of the collar so as to move the second end portion between first and second positions. The end portions have a plurality of fingers that are movable so as to be free of the surface of the duct when in the first position and which contact a rib of the duct when in the second position.
U.S. Pat. No. 7,273,238, issued on Sep. 25, 2007 to the present inventor, describes a duct coupler apparatus for joining the ends of a pair of ribbed ducts together. This duct coupler apparatus has a collar with an interior suitable for receiving the ends of the pair of ducts therein. A first coupler element is translatably secured adjacent a first end of the collar. A compressible seal is disposed between a surface of the first coupler element and the first end of the collar. A second coupler element is secured adjacent a second end of the collar. A second seal is disposed between a surface of the second coupler element and the second end of the collar. The coupler elements are translatable so as to compress the seal such that a surface of the seal will bear against a respective rib of the pair of ducts.
U.S. Pat. No. 7,686,347, issued on Mar. 30, 2010 to the present inventor, shows a coupler apparatus for use with concrete segments. This coupler apparatus has a first duct, a first coupler member having a connector, and a flexible boot extending therefrom and having an end extending over a surface of the first duct. A second duct and a second coupler member are provided. The second coupler member has a connector and a flexible boot extending therefrom and extending over an exterior surface of the second duct. A gasket is received in the connectors of the first and second coupler members for forming a liquid-tight seal between the first and second ducts. Clamps are affixed over the ends of the flexible boots so as to establish a liquid-tight seal with the respective duct.
U.S. Pat. No. 7,695,021, issued on Apr. 13, 2010 to the present inventor, teaches a coupler apparatus for use with concrete segments that has a first duct, a first coupler member connected to the first duct, a second duct, a second coupler member connected to the second duct, and a gasket member received in a channel of the connector of the first coupler member and extending outwardly therefrom. The gasket member is in compressible contact with an abutment surface of the second coupler member. The gasket member has a generally U-shaped cross-section with a curved end extending outwardly of an opening of the channel of the first coupler member. The abutment surface is a planar flanged surface extending radially transversely outwardly of the end of the second coupler member.
U.S. Pat. No. 8,398,123, issued on Mar. 19, 2013 to the present inventor, shows a duct coupling system that has a first duct with an end having threads thereon and a second duct having an end with threads thereon. A coupler is provided having a first end threadedly engaged with the threads of the first duct and a second end threadedly engaged with threads of the second duct. The ducts and the coupler each integrally formed of a polymeric material.
It is an object of the present invention to provide a duct coupler apparatus which allows for the coupling of multi-tendon ducts in precast segmental concrete structures.
It is another object of the present invention to provide a duct coupler system which allows the segmental coupler to be connected to a steel plate or anchor casting.
It is another object of the present invention to provide an apparatus and method for connecting a segmental coupler removably to a steel structure, such as an anchor, a bearing plate, a bar, or a bulkhead.
It is still a further object of the present invention to provide a duct coupler apparatus which effectively seals the interior of the steel structure during the pouring of the concrete segment and also seals the interior of the duct.
It is still a further object of the present invention to provide a method and apparatus for connecting a segmental coupler to a steel structure which is easy to install, easy to use and easy to manufacture.
These and other objects and advantages of the present invention will become apparent from a reading of the attached specification and appended claims.